As described in Patent Literature 1, a semiconductor device having a reverse conducting insulated-gate bipolar transistor (RC-IGBT) is known. In the semiconductor device, a negative voltage is applied to an insulated trench gate electrode when an IGBT device region is switched off and circulating current flows to a diode device region.
The semiconductor device allegedly allows holes flowing out from an anode region to be readily injected to a drift layer along the insulated trench gate electrode, whereby the forward voltage drop (hereinafter, “forward voltage”) can be reduced.